1. Field of the Invention
The present invention relates generally to a method and system for transmitting data to a Mobile Station (MS) over a communication network in a Digital Video Broadcast-Handheld Convergence of Broadcast and Mobile Services (DVB-H CBMS) portable broadcasting service. The present invention relates more particularly to a method and system for transmitting data related to a plurality of MS-requested Electronic Service Guides (ESGs) over a communication network.
2. Description of the Related Art
The mobile communication market faces an ever-increasing demand for new services through re-combination or convergence of existing technologies. Due to the continuing development of communications and broadcasting technologies, legacy broadcasting or mobile communication systems are now capable of providing portable broadcasting services to portable terminals (hereinafter, referred to as MSs), such as Personal Digital Assistants (PDAs). The driving forces behind a trend of converging mobile communications and Internet Protocol (IP) in future-generation mobile communication developments include: potential and actual market demands, increasing user demand for multimedia service, service providers' strategies for providing new services beyond conventional voice service, and Information Technology (IT) companies' profit and loss calculations to re-enforce their mobile communication business for meeting customer demands. In this context, portable broadcasting services are under active commercialization and standardization so that such services may be provided to MSs.
A commercial service is has been provided in compliance with DVB-H CBMS in Italy, and a commercial service based on the Nokia-Open Air Interference (OAI) standard has been provided in Vietnam. There are a variety of other standards associated with portable broadcasting services, including S/T Digital Multimedia Broadcasting (S/T-DMB), MediaFlo, DVB-Satellite services to Handheld (DVB-SH), and Open Mobile Alliance Mobile Broadcast (OMA-BCAST). DVB-H CBMS, DVB-SH, Nokia-OAI, and Open Mobile Alliance Mobile Broadcast (OMA-BCAST) commonly use a DVB-H network as a lower transmitting end and require reception of ESG data to provide a portable broadcasting service. However, the ESG data of each standard is based on a different data model, and each standard has different elements and attributes in ESG fragments.
One common requirement from service providers that provide portable broadcasting services over a DVB-H network is simultaneous transmission of ESG data over both a broadcasting network and a communication network. OMA-BCAST offers techniques for enabling convergence between a communication network and a broadcasting network in various aspects in addition to ESG data reception. Therefore, the ESG data should include guide information about communication contents provided over the communication network, as well as guide information about broadcasting contents provided over the broadcasting network. Standardization has commenced relating to transmission of ESG dam over both broadcasting and communication networks.
Typically, ESG data is transmitted to an MS in a plurality of fragments during a portable broadcasting service, and usually in two sessions. An Announcement Session includes transmission of information about how the fragments are created, information about a network over which they are transmitted, and IP address information or Universal Resource Identifier (URI) information for reception of the fragments. Hence, the MS acquires information required for ESG data reception in the Announcement Session. Based on the acquired information, the MS receives actual ESG fragments in an ESG Data Session. Aside from these two sessions, the DVB-H/DVB-SH standard defines an ESG Bootstrap Session. The ESG Bootstrap Session provides a method for selecting a particular ESG data provider and an ESG access descriptor, when there is a plurality of ESG data providers.
FIG. 1 is a diagram illustrating the configuration of the conventional ESG Bootstrap Session.
Referring to FIG. 1, an ESG Bootstrap Session 100 includes a Formal Description Technique (FDT) instance 101, an ESG provider discovery descriptor 103, and an ESG access descriptor 105. The ESG provider discovery descriptor 103 includes a list of ESG data providers, i.e. a list of ESG data servers. The ESG access descriptor 105 includes ESG data access information regarding each ESG data provider. In the illustrated case of FIG. 1, a single ESG provider exists, by way of example. Thus, an ESG single stream session 110 is configured to include an FDT instance 111, an ESG Initial (Init) container 113, an ESG Index container 115, and n ESG fragment containers 117 to 119.
A broadcasting server broadcasts this ESG Bootstrap Session 100 to an MS over a broadcasting network, or transmits it to the MS over a communication network. If particular ESG data is needed, the MS requests the ESG data from a broadcasting server or a predetermined ESG data server over a communication network. Then the server transmits the requested ESG data to the MS over the communication network. According to a DVB-H ESGolA standard document defining this process, the MS requests and receives Bootstrap information, an ESG delivery list, a container list, a complete ESG and containers in HyperText Transfer Protocol (HTTP). When requesting the information, the MS should explicitly indicate requested data using a type attribute in a message body of an ESG Query in compliance with the HTTP/1.1 standard. For example, to request necessary containers, the MS sets type=ESGContainer in the HTTP/1.1 message body. Then the server transmits the containers to the MS.
When the MS requests ESG data over the communication network, it receives the ESG data in containers or fragments defined by the DVB-H CBMS standard. If the MS requests two or more data files, it cannot receive them at one time. For example, when the MS should receive a plurality of containers, it first receives a container list from the server and re-requests each container included in the container in HTTP. The repeated requests and responses are time consuming, thereby increasing the cost of using the communication network.